Retractable landing gear



' May s, 1936. G. LOENING 2,039,813

RETRACTABLE LANDING GEAR Filed Aug. 5, 1933 2 Sheets-Sheet 1 INVENTOR 7ZZIZMA BY ATTORN Y May 5, 1936. G. LOENING RETRACTABLE LANDING GEARFiled Aug. 5, 1933 2 Sheets-Sheet 2 11v VENTOR ATTORN Y Patented May 5,1936 PATENT OFFICE- RETRACTABLE LANDING GEAR Grover Loening, Mill Neck,N. Y., assignor to Grover Loening Aircraft Company, Inc., Garden City,N. Y., a corporation-of New York Application August 5, 1933, Serial No.683,775

3 Claims.

This invention relates to retractable landing gear for aircraft.

An object of the invention is to provide an improved retractable landinggear which is economical to manufacture, reliable, and convenient andadvantageous in use.

Another object of the invention is to provide a retractable landing gearin which a wheel unit is pivotally connected to a radius arm whichswings to raise and lower the landing gear, and has an abutment forlimiting the pivotal movement of the wheel unit and for holding it inlanding position. v Another object is to provide a landing gear having awheel unit pivotally connected to a swinging radius arm and heldin'landing position by a fixed-length strut which can be folded toretract the landing gear.

Another species of the invention claimed herein no is disclosed in mycopending application Serial No. 595,796, filed February 29, 1932 (nowPatent No. 1,921,992, dated August 8, 1933).

Other objects, features and advantages of the invention will appear orbe pointed out as the specification proceeds.

In the accompanying drawings, forming part hereof: Fig. l is a frontview, mostly insection and partly diagrammatic, showing one-half of alandbeing shown in landing position;

Fig. 2 is a front elevation showing the landing gear of Fig. 1 in foldedor retracted position;

Fig. 3 is a view taken on the line 3-3 of Fig. 1;

Fig. 4 is an enlarged'detail sectional view along the line 4-4 of Fig.1; and v Fig. 5 is a section along the line 5-5 of Fig. 1. A radius armIII has a pivot connection l2 to a fitting l4 fixed to the airplane bodyIt. The

140 radius arm can swing in a vertical plane about this pivotconnection, and has a bifurcated extension formed by two channel platesll which are welded to the sides of the radius arm and form hornsprojecting beyond the end of the arm.

A stub axle 22 extendsbetween the horns 20. This stub axle is pivotallyconnected to the radius arm by a pin 24 extending through the axle andthe horns 20.

A tongue 26 on the inner end of the stub axle 22 50 fits into a groove23 in the radius arm, and the tongue bottoms against anabutment 30 atthe lower end of the slot to limit the pivotal movement of the stub axlewith respect to the radius arm. The tongue 23 comes into contact withthe 55 abutment 30 when the gear is in landing position,

ing gear embodying this invention, the structure as shown in Fig. 1.Instead of the abutment 30 at the. lower end of the groove 28, thebottom of the groove can be made to serve as an abutment if sloped withrespect to atangent to the are described by the tongue 26. 5

The stub.axle 22 has upwardly extending ears 32 and a pivot connection34 to a strut 35. This strut is foldable as a toggle and comprises upperand lower fixed length links 38 and 40, respectively, connected by anoffset hinge 42. The upper end of the link 33 has a pivot'connection 44to the body of the airplane so that this link can swing in a verticalplane.

The axis of the offset hinge 42 is parallel to that of the pivotconnection 44, and the hinge 42 is offset to the airplane side of thestrut so that the strut folds outwardly as the landing gear isretracted. The links 38 and 40 are substantially parallel and verticalwhen the landing gear is retracted, as shown in Fig. 2. The principaladvantage of folding the strut outwardly is that the links 33 and inswing away from the airplane, and it is not necessary to build theairplane with a recess for the strut to swing through, such as would berequired if the strut folded inwardly. The avoidance of such recesses isparticularly important in the case of hulls or pontoons of amphibianaircraft.

When the landing gear is in landing position, as shown in Fig. 1, thestrut 36 is straight, and since the hinge 42 is offset, the strut isautomatically locked against folding under its compression load. In itsstraightened position the strut comprises a fixed length compressionmember and has no pivotal movement on either of the connections 34 and44.

The strut 38 is folded and straightened to raise and lower the landinggear by a gear segment 43 connected with the upper end of the link 38 atits pivot connection 44. The gear segment 45 meshes with a pinion on ashaft 52. The pinion .50 is rotated by a sprocket wheel 54, which isdriven by a chain 56 from a manually operated sprocket 53. The aviatorturns the sprocket 58 in one direction to lower the landing gear and inthe opposite direction to retract it.

A wheel is carried by the stub axle 22 and a shock absorber isbuilt intothe wheel. The shock absorber is shown diagrammatically in Fig.

1. A wheel having a balloon tire as its only 50 shock-absorbing meanscanbe used in place of the shock absorbing wheel '50, but smootherlandings are obtainedwlth the shock absorber.

By using a fixed length strut and having the shock-absorbing means inthe wheel it is possible to have the wheel substantially vertical whenin landing position even though not loaded. In,

landing gears having compressible struts as shock absorbers, the wheelstoe in sharply toward the bottom before the landing gear is fullyloaded. The advantage of a vertical wheel is apparent from Fig. 1. Thepoint of contact of the wheel 60 with the ground is well out from thepivot pin 24 so that the landing shock can be at a substantial angle tothe vertical and the line of force still pass outside of the pivot pin24. As long as this line of force passes outside of the pivot pin 24,the force tends to turn the wheel unit counterclockwise about the pin 24and such movement is prevented by the abutment ll.

If the airplane lands across the wind with considerable leeway, or forsome other reason the landing shock has a large horizontal component, sothat the force against the wheel when it strikes the ground is in a linepassing inside of the pivot pin 24, then the wheel unit tends to rotatein a clockwise direction about the pin 24 and tends to move the tongue26 away from the abutment 30. Cables 66 are fastened to the airplane at66 and the other ends of these cables are connected with the cars 32 ofthe stub axle. These cables hold the whee unit from turning clockwise onthe pivot pin 24 when the radius arm l0 and wheel unit are in landingposition. The points of connection 66 are sufficiently above the pivotconnection l2 so that thecables 66 do not prevent relative clockwise Imovement of the wheel unit on the pin 24 when the radius arm is swung upinto ,a substantially vertical position, as shown in Fig. 2.

The radius arm I 6 is braced against forward and aft movement by a draglink 10 (Fig. 3), which is fastened rigidly to the radius arm ill by thepin 24. The drag link 10 has a pivot connection 12 to a fitting 14 onthe airplane. The radius arm I0 and drag link I0 comprise means forguiding the movement of the wheel unit as it is raised and lowered.

Figs. 4 and '5 show enlarged detail sectional views of the tongue andslotconstruction and abutting surfaces of the radius arm 10 and stubaxle 22. The radius arm is shown constructed from a tube having asolid'plug 82 closing its end. The slot 28 extends ony part way throughthe plug 82, and the end of this slot comprises the abutment 30 withwhich the tongue 26 contacts to limit further pivotal movement of thestub axle.

The preferred embodiment of the invention has been described, butchanges and modifications may be made, and various features of theinvention used alone or in combination with other features, withoutdeparting from the invention as defined in the claims.

I claim:

1. A retractable landing gear for aircraft comprising a radius arm; awheel unit pivotally connected to the radius arm; means for swinging theradius arm to raise and lower the wheel unit; and means to preventpivotal movement of the wheel unit with respect to the radius arm whenlowered into landing position including abutments for holding the wheelunit against movement by forces acting within a given angular range froma vertical plane, and a cable for preventing pivotal movement of thewheel unit by side thrust against Y the bottom of the wheel and beyondsaid angular range.

2. An aircraft landing gear comprising a radius comprising a wheel unitincluding shock-absorbing means, and a stub axle; means for guiding themovement of the wheel unit including a radius arm and horns extendingfrom the radius arm and pivotafly connected to thestub axle of the wheelunit; a tongue on theend of the stub axle between the horns in positionto fit intoa groove in the radius arm; an abutment at one end of thegroove for limiting the movement of the tongue in the groove and thepivotal movement of the stub axle with respect to the horns; a strutpivota-lly connected to the airplane and wheel unit, and comprisingupper and lower fixed-length links connected together by an offset hingeon which the strut folds outward as the landing gear is moved intoretracted position.

